Biodiesel, diesel fuel made from a biological source such as microalgal oil or soybean oil, is an important alternative to petroleum derived diesel. Algae are potentially a superior source of oil than plants such as soybeans because they are theoretically capable of producing more oil per acre of land/space required to grow them: for example, algae could theoretically produce 20-times the oil per acre than soybeans. Algae can be grown on non-agricultural land using little water, avoiding controversy over the diversion of food and food-production resources to fuel production when there are starving people in the world.
Triacylglycerol (TAG) is the precursor molecule of biodiesel, defined as fuel comprised of fatty acid methyl esters, and algal growth systems have the potential to produce TAG to a larger degree than land-based plant systems. Furthermore, particular fatty acid chains are desirable for altering the physical characteristics of biodiesel (e.g. gel point) or for secondary market use (e.g. nutraceutical market—omega-3 fatty acids).